This is a problem that WordPress devs know about. They don’t follow the same locale requirements as Facebook. In one of the next updates I’ll be allowing the filtering of get_locale() so this won’t be a problem in the future.

well according to your page source you’re still on v2.0.2 no .3. Also wordpress has an issue with japan locale by spitting it out as a 2 letter instead of the standard four with an underscore. It’s a known issue I hope they diagnose soon.